John Zawahri gave no clue about the motive for his deadly rampage, police say.

The gunman who killed five people last week during a shooting rampage through Santa Monica left an "almost conversational" farewell note expressing remorse for killing his father and brother, law enforcement authorities said Thursday evening.

John Zawahri, 23, also wrote that he hoped his mother would be cared for financially and said goodbye to several friends.

At a news conference, police gave their most detailed account yet of Zawahri's trail of bloodshed June 7 as he made his way from his father's home on Yorkshire Avenue and along busy Pico Boulevard before storming onto the Santa Monica College campus, where he was fatally wounded by officers in the library.

Police have said Zawahri fired about 100 rounds in a wave of violence that lasted 13 minutes and spanned more than a mile.

Santa Monica Police Chief Jacqueline Seabrooks said authorities found replica weapons and zip guns during a search of Zawahri's bedroom at his father's house. She also said the state Department of Justice denied him a firearm in 2011.

"He had an affinity for weapons," Sgt. Richard Lewis told reporters Thursday. "He had gun magazines, different shooting magazines, all different resources."

Police found at least four replica air-soft-like guns in Zawahri's home, as well as knives. They also found zip guns capable of firing live ammunition.

Seabrooks said Zawahri attempted to buy a weapon in 2011, but for reasons that are unclear, the state's Department of Justice deemed him ineligible.

Despite the denial, police say, Zawahri proceeded to buy gun components from various sources across the country and assemble his own semiautomatic rifle.

Police said they believe Zawahri's AR-15-style weapon consisted of an "80%" lower receiver that was not fully manufactured. Because of its incomplete status, it would not require a serial number or registration.

"In this particular case, the weapon that he ended up with ultimately is one that, by definition, would be illegal to possess here in the state of California," Seabrooks said.

The police chief said the revolver Zawahri was also carrying had been converted.

Also on Zawahri's body, authorities said, was a three- to four-page handwritten note. A portion dealt with family, but most of it was a series of farewells to "several" friends, Lewis said, adding that there was no hatred apparent. Police plan to interview the friends as the investigation continues.

"In the note was commentary that he was sorry for having killed his father, sorry for having killed his brother, that he hoped his mother would be looked after financially and would receive financial recompense from his father's estate," Seabrooks said. "He said goodbye to friends and it was more of a farewell."

Despite the letter, Zawahri's motive for the shooting remained unclear, police said.

Lewis said he did not know if Zawahri was born in the United States. Police said his religious background was unclear, but said there was no indication that religion played a role in the attack.

"We know he lived a troubled life and that he experienced mental health challenges," Seabrooks said. "We believe that his mental health challenges likely played a role in his decisions to shoot and kill."

Authorities have said Zawahri first killed his father, Samir, 55, and older brother, Christopher, 25, before heading for the college.

On Thursday, police specified that both were killed in the same room in the back of the Santa Monica home. Zawahri then carjacked a motorist and forced her at gunpoint to drive him to the campus.

Along the way he fired on other vehicles, including a sport-utility vehicle carrying Santa Monica College groundskeeper Carlos Franco, 68, and his daughter, Marcela, 26. Both died.

Police identified his last victim as Margarita Gomez, a 68-year-old visiting the campus to collect cans.

As the rampage reached its final stages, two Santa Monica police officers and one Santa Monica College officer ultimately "neutralized" the gunman, authorities said.